1. Technical Field
The present invention relates antenna devices and more particularly such devices for use with portable electronic devices such as electronic wristwatches and a method of making the antenna devices.
2. Background Art
Some electronic wristwatches include a radio wave timepiece with a built-in antenna. Japanese patent publication 2002-98780 discloses a wristwatch that includes an antenna device disposed in an antenna reception space near and within a plastic case on a straight line connecting the center of the wristwatch and a band attachment provided on the outer periphery of the case. The antenna device comprises a bar antenna around which a coil is formed.
In this antenna device, the bar antenna around which the coil is formed is effective to receive radio waves of a long wavelength, but ineffective to receive radio waves of a short wavelength or a high frequency. Thus, the antenna device is not suitable for a GPS antenna that receives radio waves of a short wavelength from artificial satellites to specify the user's location. Furthermore, the antenna device requires forming a coil around the core, which is troublesome, expensive and makes the resulting antenna device weighty.
It is an object of the present invention to provide an antenna device that is easy to make, light in weight, and capable of receiving radio waves of a short wavelength with high sensitivity, and a method of making the antenna device.
Another object is to provide an antenna device that is easy to attach and connect and capable of receiving radio waves of a predetermined wavelength with high sensitivity.